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What Is A ‘Screening Test’?

Issue 6.15

I am frequently asked to do specialty tests for patients because they want to be ‘screened’ for certain disorders or cancers.  If a patient is having problems that need addressed, ordering specific tests focusing on those problems is appropriate but these are called ‘diagnostic’ tests as we are using the tests to help ‘diagnose’ what is wrong with a patient.

To be a ‘screening’ test, it needs a few things:

1) The test needs to be able to detect a disease process at an early enough to stage to affect morbidity or mortality (in other words, it needs to find the cancer or disease early enough on the test to make a significant difference on the outcome of the disease process or death);

2) it must be minimally invasive;

3) it must be cost effective,

4) it must have a high specificity and sensitivity (in other words, it must have a high accuracy for detecting the disease at the time and a high rate for ruling out the disease if it isn’t truly there).

If the test can’t meet these criteria, it is a poor ‘screening’ test and shouldn’t be ordered until there are symptoms that warrant doing so.  Let me use for example a chest x-ray for lung cancer.  I am frequently asked to do this but I explain to patients that by the time you see something on a chest x-ray, it is too late.  The disease process is advanced enough it is no longer preventative on making a large change on the outcome of the disease process but would be ‘diagnostic’ of lung cancer which is already advanced.  However a chest CT (cat) scan can be used as a preventative tool.

If you are in need of a physical health exam to get your screening tests set up as appropriate for you see Karen Radley, MD for this. 435-673-9653.

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